This disclosure generally relates to a fuel vapor processing apparatus that may include a canister for adsorbing fuel vapor produced in a fuel tank. The fuel vapor adsorbed by the canister may be desorbed and purged to an engine.
A known fuel vapor processing apparatus including a canister for adsorbing fuel vapor produced in a fuel tank is typically configured such that the canister adsorbs the fuel vapor during refueling to the fuel tank. Therefore, it may be optimal if the canister adsorbs the entirety of the fuel vapor produced during refueling. Japanese Laid-Open Patent Publication No. 2002-332921 discloses a fuel vapor processing apparatus in which the concentration of fuel vapor contained in a purge passage is detected for controlling a purge operation such that the detected concentration does not exceed a predetermined value.
In the fuel vapor processing apparatus disclosed in Japanese Laid-Open Patent Publication No. 2002-332921 a control is performed to promote the purge operation for reducing the quantity of fuel vapor adsorbed by the canister if the concentration of fuel vapor in the purge passage is relatively high while the quantity of fuel vapor adsorbed by the canister is relatively large. However, in the case of this control, because it cannot specify the time when the refueling operation is performed, the fuel vapor is not necessarily desorbed enough from the canister and purged to the engine to an extent that the canister can adequately adsorb fuel vapor produced in the fuel tank when the refueling operation is performed.
In view of the challenges discussed above, there is a need in the art for a technique of enabling a canister to adequately adsorb fuel vapor produced in a fuel tank when a refueling operation is performed.